This invention relates to an electronic component cooling apparatus, and more particularly to an apparatus for cooling electronic components incorporated in an electronic appliance such as a microprocessor unit (MPU) or the like.
Recently, a microprocessor unit tends to be increased in integration so that performance thereof may be enhanced. Unfortunately, this causes generation of heat from the microprocessor unit to be substantially increased, so that it is required to cool the unit. In order to solve the problem, an electronic component cooling apparatus called an MPU cooler is employed for forcibly cooling the microprocessor unit per se.
Japanese Utility Model Publication No. 15982/1991 discloses an electronic component cooling apparatus, wherein a fan mounting plate is mounted on a heat sink and then an axial fan commercially available is mounted on the fan mounting plate. The axial fan commercially available is so constructed that an impeller which includes a plurality of blades and is mounted on a rotor of a motor is fully housed in a casing provided therein with a cylindrical air duct.
Also, U.S. Pat. No. 5,309,983 discloses an electronic component cooling apparatus including a heat sink formed with a fan holding recess, in which a commercially available fan is fittedly held.
U.S. Pat. No. 5,288,203 discloses an electronic component cooling apparatus, wherein a fan specially designed in such a manner that an impeller is not enclosed with a casing or the impeller is partially enclosed with or partially exposed from the casing is mounted on a heat sink. A portion of the casing exposed from the casing is received in a space defined by a plurality of radiation fins fixed on the heat sink, wherein the casing is fixed directly to the heat sink.
Direct fixing of the casing for the fan to the heat sink is carried out by adhesion techniques or by means of a plurality of fitting and/or engagement structures. The engagement structure is typically disclosed in, for example, Japanese Patent Application Laid-Open Publication No. 339244/1994 and Japanese Patent Application Laid-Open Publication No. 15914/1995. In Japanese Patent Application Laid-Open Publication No. 15914/1995, an engagement structure is disclosed wherein a casing for a fan and a heat sink are rotated relatively to each other for releasing engagement therebetween. In the structure, it is required to provide a space which permits the fan casing and heat sink to be rotated relatively to each other.
However, the prior art constructed as described above fails to permit the fan casing and heat sink to be disengaged or separated from each other after assembling of the electronic component cooling apparatus or mounting of the electronic component cooling apparatus on an electronic appliance. Even when the apparatus may be constructed to separate both from each other, it requires the above-described space for rotation. Also, relative rotation between the fan casing and the heat sink causes wearing at a contact region therebetween.